Hi guys buying a nearly new mac

If you click on the About This Mac link just below the Apple logo it will open a window the has the serial number and other important information.

Check Your Service and Support Coverage - Apple Support

Apple does not get involved with Allegations of theft of its devices.

(consider an ugly divorce to understand why the word allegations is used above.)

There is no 'master list' of stolen devices, at least not one that Apple maintains.

You will also need to get the Mac's password in order to operate it.